Restore of VM fails with "Cannot open disk" "Error 1 (Unknown error)" error

Products

• VMware vSphere ESXi

Issue/Introduction

This article outlines troubleshooting steps for VM Restoration from Arcserve backup tool which encounters an issue at the initial stage when attempting to open the disk.

Symptoms: 

• VM restore fails with "Cannot get compatible version for vim".
• VM restore from Arcserve backup fails at initial stage in opening the disk.
• vCenter connection timeout after few seconds.

You may observe similar errors in the VDDK log.

2024-07-17 07:35:52.450 VixDiskLib: VixDiskLibConnectInt: Failed to start session. Cannot get compatible version for vim at 5713.
2024-07-17 07:35:52.466 VixDiskLib: VixDiskLib_ConnectEx: No transport plugin. Advanced transports not available.
2024-07-17 07:35:52.481 VixDiskLib: VixDiskLib_FreeConnectParams: Free connection parameters.
2024-07-17 07:35:52.591 VixDiskLib: VixDiskLib_OpenEx: Open a disk.
2024-07-17 07:35:53.638 VixDiskLib: VixDiskLib_OpenEx: Failed to start session. Cannot get compatible version for vim at 7111.
2024-07-17 07:35:53.653 VixDiskLib: VixDiskLib_Open: Cannot open disk [VMFSVol_***] VM123/VM123.vmdk. Error 1 (Unknown error) at 7212.

As per Arcserve backup vendor they follow bellow API calls policy.

1. Call VixDiskLib_InitEx() in main thread.
2. Other threads are created after VixDiskLib_InitEx() completes.
3. Then call VixDiskLib_ConnectEx in any thread.

It is necessary to have thread ID printed in VDDK logging with verbose and log level can be set to 6. You may observe below symptoms.

1. Please don't add port 443 to VixDiskLibConnectParams.serverName. (just set it as vCenter name in this case)
2. Leave port as 0 unless vCenter server https port is specially configured as other port number.

Environment

VMware vSphere ESXi 8.x
VMware vSphere ESXi 7.x

Cause

Improper configuration of connectParams can lead to a failure in data restoration initiated by the Arcserve backup tool.

Resolution

For a successful data restore "no port" is specified to connectParams.

Parameter VixDiskLibConnectParams *connectParams when call VixDiskLib_ConnectEx:

no port specified in connectParams->serverName

no port specified for connectParams->port